The present invention generally relates to instrument calibration. In particular, the present invention relates to a universal calibration device for electromagnetic calibration of clinical instruments.
In medical and surgical imaging, such as intraoperative or perioperative imaging, images are formed of a region of a patient's body. The images are used to aid in an ongoing procedure with an instrument (e.g., a surgical tool, imaging tool, diagnostic tool, etc.) applied to the patient and tracked in relation to a reference coordinate system formed from the images. Image-guided surgery is of a special utility in surgical procedures such as brain surgery and arthroscopic procedures on the knee, wrist, shoulder or spine, as well as certain types of angiography, cardiac procedures, interventional radiology and biopsies in which x-ray images may be taken to display, correct the position of, or otherwise navigate a tool or instrument involved in the procedure.
Medical navigation systems track precise locations of surgical instruments in relation to multidimensional images of a patient's anatomy. Additionally, medical navigation systems use visualization tools to provide the surgeon with co-registered views of these surgical instruments with the patient's anatomy. To help ensure tracking accuracy, instruments should be calibrated with respect to the medical navigation system.
Computer-assisted methods now provide real-time navigation during surgical procedures, including analysis and inspection of three-dimensional (3D) diagnostic images from magnetic resonance (MR) and computed tomography (CT) data. Instrumentation has also undergone rapid development, providing instrumentation for use in small body cavities and minimally invasive procedures. The combination of instruments and computer-generated 3D images may help to overlay instrument tracking information with volumetrically reconstructed patient images in a surgical field. Thus, surgeons can look beyond visible surfaces and provide “on-the-fly” 3D and two-dimensional (2D) information for planning and navigational purposes.
Tracking systems may be ultrasound, optical, inertial position, and/or electromagnetic tracking systems, for example. Electromagnetic tracking systems may employ coils as receivers and transmitters. Electromagnetic tracking systems may be configured in sets of three transmitter coils and three receiver coils, such as an industry-standard coil architecture (ISCA) configuration. Electromagnetic tracking systems may also be configured with a single transmitter coil used with an array of receiver coils or an array of transmitter coils with a single receiver coil, for example. Magnetic fields generated by the transmitter coil(s) may be detected by the receiver coil(s). For obtained parameter measurements, position and orientation information may be determined for the transmitter and/or receiver coil(s).
Due to many parameters involved in typical instrument function, however, small errors in settings of the instrument may have relatively large and cumulative effects such as contributing to a discrepancy between image data position and tracked position. Thus, there is a need for more precise calibration of an instrument and accuracy testing of the calibrated instrument.